(i) Proteins are biopolymers of amino acids which condense together forming peptide bonds.
(ii) Oligopeptides on hydrolysis give 3 to 12 \(\alpha \)-amino acids, where as polypeptides give large number of \(\alpha \)-amino acids on hydrolysis.
(iiI) When tertiary structure of protein is ruptured by,protein p^H or on heating, protein is said to be denatured.It lose its biological activity.

(a)The process of disruption of higher structure without changing its primary structure is called denaturation. If the disruptive agent is removed and protein recovers its original structure, it is called renaturation.
(b)In stomach pH is acidic, therefore, amylase becomes inactive, that is why digestion of carbohydrates does not take place in stomach.

(a) Isoelectric point: It is the pH at which +ve and -ve charges on zwitter ion are equal, e.g., amino acid exists as zwitter ion at pH =5.5 to 6.3.
(b) Mutarotation : It is a spontaneous change in optical rotaion when an optically active substance is dissolved in water, e.g., \(\alpha\)-glucose, when dissolved  in water, its optical rotaion changes from 111^o to 52.5^o.
(c)Enzymes : They are biological catalysts which catalyse specific biochemical reactions, e.g., 
\(\underset { sucrose }{ C_{ 12 }H_{ 22 }O_{ 11 } } +H_{ 2 }O\quad \overset { invertase }{ \longrightarrow } \underset { Glucose }{ C_{ 6 }H_{ { 12 } }O_{ 6 } } +\underset { Fructose }{ C_{ 6 }H_{ 12 }O_{ 6 } } \)
Most of enzymes are globular proteins.

(i) Co-enzymes : Those prosthetic groups which get attached to enzymes at the time of reaction are called co-enzymes. These increase the activity of enzymes.
(ii) Mutation in Biomolecules : A difference of a single base in DNA molecule can cause change in amino acid sequence which leads to mutation.
(iii) Nucleotides : They are monomers of nucleic acids. They consist of heterocyclic base, pentose sugar and phosphoric acis residue.

(i) Vitamin A deficiency leads to night blindness. Its sources are fish oil, carrot, etc. 
(ii) Vitamin B₆ deficiency leads to convulsions. Its sources are cereals, grams, yeast, etc. 
(iii) Vitamin E deficiency leads to loss of reproductive power. Its sources are germ oil, cotton seed oil, sovabean oil , etc

(i) Those carbohydrates which have free aldehyde group and reduce Fehling's solution are called reducing sugars.
(ii) When tertiary and secondary structures of protein is ruptured by heating, change in pH or by adding electrolyte it is called denaturation of a proteins.
(iii) We take oxygen from atmosphere and release CO₂. Plants take CO₂ and H₂O from atmosphere to prepare their food in presence of sunlight and release O₂ and thus O₂ is replenished in our atmosphere. 

(i) Mutarotation : The spontaneous change in specific rotation of an optically active compound is called mutarotation when it is dissolved in water. When glucose is crystallised from a concentrated solution at 30^oC, it gives glucose having [\(\alpha\)] = +111^o. Its specific rotation changes to 52.5^o. when it is dissolved in water. It is because \(\alpha\) glucose changes into \(\beta\) glucose. This changes is optical rotation is called mutarotation.
(ii) Multiple deficiences caused by lack of more than one vitamin in human being is called avitaminosis.

Those carbohydrates which reduce Tollen's reagent to give silver mirror or form brick red ppt. With Fehling's solution are called reducing sugars, whereas those which do not are non-reducing sugars.
All monosaccharides are reducing sugars due to the presence of aldehyde group or \(\alpha\)-keto.
Those disaccharides like sucrose are not reducing sugar because aldehydic and ketonic groups are linked and not free. All polysaccharides are not reducing.